Personnel working in rivers, streams, ponds or other bodies of water (hereinafter, for purposes of this description, referred to as rivers) often disturb the sediments of the bed. Such activities could include pipeline installation, road and bridge construction, etc. These sediments flow downstream or move offsight, causing damage to the environment.
In flowing waters, sediments are currently trapped by staking bales of hay on the riverbed downstream of the work site. After the sediments have been trapped in the bales, the bales are removed from the river or stream.
The hay bale methodology is not entirely effective, since sediments do tend to pass under and around the gaps in the individually staked bales. Also, sediment that comes to rest atop or in front of the bales is often washed away when the bales are removed from the water. Furthermore, the hay bales are not usable in streams or rivers deeper than two feet, or those having high velocity flow.
The present invention seeks to overcome the disadvantages of the hay bale method.
The invention features a number of porous mats designed to stem the dissemination of loose sediments in the flowing current. The mats are laid horizontally on the riverbed immediately downstream from the work site. Porous, the mats are designed to entrap sediment particles that come to rest on or flow through their surfaces. The porous mats comprise woven mesh filled with several inches of absorptive material such as straw or excelsior. Hardwood stays maintain the configuration and can be grasped to facilitate installation and removal. The mats have corner and side eyelets for staking them to the bottom of the river to facilitate handling and later for staking them to the river bank.
As indicated above, one application of this invention is to remove the mats after use, laying them upon the riverbanks. In this embodiment, the sediment-rich mats can be seeded to grow vegetation that beautifies and stabilizes the berm. In addition, since the mats can be completely biodegradable, they may require no subsequent disposal after staking them to the bank. Thus, the sediment mats can serve a dual purpose.
The upper, sediment-permeable surface of the mat is loosely woven to allow the sediment to pass into the mat, which then filters down into the center absorptive layer. The lower sediment-impermeable layer of the mat is tightly woven in order to ensure that the trapped sediments do not escape.
The low profile of the porous mats, vis-a-vis that of the bales of hay, has the advantage of not disturbing or changing the speed of the water flow. In other words, the mats are non-invasive with respect to the river environment. They can be used in rivers and streams of varying depth, particularly those having a depth greater than two feet. The mats can be easily stored and transported in rolls.